A233552 - OEIS

A233552

Odd integers k such that for every m >= 1 the numbers k*4^m - 1 have at least three prime factors, not necessarily distinct, and k*4^m - 1 has at least two-element covering set.

%I #31 Aug 14 2021 21:55:09

%S 361,919,1681,1849,2419,2629,3301,5209,5539,5581,6421,7771,8551,9109,

%T 9871,10039,10609,10819,11491,13399,13729,13771,14611,15661,15961,

%U 16741,17299,18061,18229,18799,19009,19681,21589,21919,21961,22801,24151,24931,25489

%N Odd integers k such that for every m >= 1 the numbers k*4^m - 1 have at least three prime factors, not necessarily distinct, and k*4^m - 1 has at least two-element covering set.

%C Here an n-element covering set is a minimal set of n distinct primes such that at least one of these primes divides every integer in the sequence k*4^m - 1, m >= 1. - _Arkadiusz Wesolowski_, Jul 21 2021

%K nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Dec 12 2013

%E Name corrected by _Arkadiusz Wesolowski_, Jul 21 2021